Mounting NAS to save recordings to

I am actually using Openelec on my Raspberry pi and have started to use the TVHeadend front and back end features.

I have been able to get the device to watch live TV and have also been able to record TV to the Pi's SD card storage.

I tried to mount the CIFS share from my NAS to record to and it worked. But when I record something to the NAS it creates a file with the correct name but the size is always 0KB, even if i record for 1hr+.